Structural reasons for the chambers above the burial chamber?
It is argued that these small compartments were built above the ceiling of the burial chamber to relieve the stress of weight that could crack the chamber's ceiling. Some 38 blocks or more, each weighing about 50 to 80 tonnes were placed on top of the ceiling. Above these four granite chambers is a limestone gable, which it is said, was designed to distribute the weight to the north and south walls of the burial chamber. Modern architects and engineers disagree that these chambers function to relieve or distribute the weight of the pyramid pushing down on the chamber below. Why have so many chambers when a single gable could be built above the flat ceiling of the King's chamber to distribute the weight from above to the walls? One might even ask why the Queen's chamber, being situated lower in the pyramid's structure and made of a softer and therefore less structurally sound stone, would not need similar protection.
In a conversation with engineer Rudolf Gantenbrink he told me that he thought the term 'relieving chambers' was a misnomer invented by people who, in his words, "have not the slightest idea about technical realities".
From an engineering perspective, Rudolf suggests that without these upper chambers the roof beams of the King's chamber, which deflect about 50% of the load into the horizontal, would have pushed against the south end of the Grand Gallery. To avoid this, he says that the builders had to lift the roof above the relevant static structure of the Grand Gallery. Other Engineers have supported this view.
On the face of it this explanation seems more plausible than the 'relieving chamber' theory but if this is, in fact, the reason for the necessity for the construction of these chambers then the north-south position of the King's chamber must have been either very badly planned or extremely important. This problem would have certainly been obvious to anyone looking at the plans of the building. Had the King's chamber been located slightly further to the south (away from the Grand Gallery), the necessity for the inclusion of these upper chambers, according to this theory, could have been avoided completely.
Was it really accident that placed the King's chamber too close to the south wall of the Grand Gallery resulting in the need to raise the roof of the King's chamber over 51 feet higher than originally designed? If so, then are we to understand that the builders just happened to have all that extra granite lying around the site that they could use? If not, then they would had to have made an extra trip all the way down the Nile to Aswan, a distance of more than 800 kilometres, to quarry the extra granite necessary for the job.
If you roll your mouse over the picture above, an alternative layout can be seen in which the supposed problem of the gabled vault above the King's Chamber pushing on the south end of the Grand Gallery is avoided simply by moving the passage system up and to the north of its present position. The quarrying, dressing, transporting and positioning high in the upper region of the pyramid of some two to three thousand tonnes of granite could have been easily avoided in this way had the builders been concerned about the proximity of the vaulted ceiling of the King's Chamber to the Grand Gallery's south wall.
Clearly therefore, the granite chambers above the burial chamber were not included in the design for structural reasons, rather they were built to complete a very important part of the symbolism portrayed by the pyramid's complete substructure.
An interesting feature that should be mentioned while on the subject is the bowl-shaped hollows in the beams that make up the floor of the upper most chamber, otherwise known as Campbell's chamber.
Bowls in Campbell's chamber
For what use these basins were intended is another mystery. According to Petrie's analysis, these might have been to hold the butt ends of beams which supported the sloping roof-blocks during the building. It is possible, however, that oil, water or honey or some other purifying substance was poured into the bowls. Purification bowls have been found from the Old Kingdom such as the nine alabaster bowls found in the court of Niuserre's sun temple. These measure about 1.18 meters in diameter. Borchardt suggested that they may have been used to store the blood of slaughtered sacrificial beasts but this has been doubted due to the lack of the accompanying evidence that is usually found at such sites.
Fifth Dynasty Purification Bowls
Niuserre's Sun Temple
The pouring of purifying liquid into the bowls inside the top 'relieving' chamber could have been viewed as anointing the crown of the gigantic statue of Osiris, or anointing the Djed Pillar inside the pyramid of the Khnum-Khufu.